A tuberculin test (++) indicates a positive result. Active tuberculosis is determined by intradermal injection of tuberculin and observation for 72 hours. If the erythema is <5mm, it is a negative result, suggesting no previous TB infection and no vaccination. If the erythema is 5-10 mm after the combined bacteriocin test, it is a (+) result, suggesting a weak positive. An erythema of 10-20 mm on the tuberculin test is (++), still suggesting a possible previous TB infection or BCG vaccination. If the tuberculin test shows a strong positive result, manifested as >2cm, or blisters, ruptures, or hard nodules, it is a strong positive result, and tuberculin infection should be suspected and treated at a designated infectious disease hospital.